Flap Dimensions:
6"w x 11”h
The entry way your dog goes through.
Height To Raise Window
18 1/2"
How high you must raise your window in order to fit the panel into the track.Thermo Sash 3e Pet Door for Sash Windows
- Innovative Thermo Sash 3e Pet Door designed for sash windows, perfect for renters and vacation homes
- Energy-efficient design featuring Low-E glass, sturdy aluminum framing, and insulating flap, ensuring temperature regulation
- Accommodates various pet sizes with four flap sizes available, fitting cats to large breed dogs
- Easy installation requiring just minutes and a 1" wide window track, making it a convenient option for any home
- Secure and protective with a molded ABS plastic locking cover, providing peace of mind and protection for your pet
- Extra Large Flap 22" - 25" Width Panel is all metal (no glass), custom-made-to-order, and non-returnable
Extreme Weather Resistance
Install Multiple
Easy Installation in Minutes
Product Details
-
High-quality construction: Thermo Sash 3e Pet Door features a sturdy aluminum frame and Low-E glass for added durability and insulation
- Energy-efficient flap: Insulating flap with a complete magnetic seal, designed to stay closed in winds up to 50mph, keeping your home comfortable and protected
- Flexible installation: Easy to install in minutes, with no permanent alterations required, making it ideal for renters and vacation homes
- Fits various sash window sizes: Designed to fit all vertical sliding sash window widths with a track width of at least 1"
- Suitable for all pets: Available in four sizes to accommodate cats and large breed dogs
- Customizable flap position: Easily switch the side of the panel the pet door is on to suit your needs and preferences
- Insulation and weather resistance: Draft stopper and weatherstripping included for added insulation and protection against the elements
- Extra-large panel option: All-metal panel with no glass for the Extra Large Flap 22" - 25" Width, custom-made-to-order, and non-returnable
- Lifetime warranty: Ensuring peace of mind and long-lasting satisfaction
- Innovative design: Combines the convenience of a pet door with the insulation and energy efficiency of modern windows
Please note that the Extra Large Flap 22" - 25" Width Panel is all metal (no glass in the panel), custom-made-to-order, and non-returnable.
Need help Installing? Take a look at our Thermo Sash Installation page.
Size Chart
- Small6"w x 11"h
- Medium 8"w x 15"h
- Large 10"w x 19"h
- Extra Large 12"w x 23"h
Flap Dimensions:
8"w x 15"h
The entry way your dog goes through. Height To Raise Window
22 1/2"
How high you must raise your window in order to fit the panel into the track.Flap Dimensions:
10"w x 19"h
The entry way your dog goes through. Height To Raise Window
26 1/2"
How high you must raise your window in order to fit the panel into the track.Flap Dimensions:
12"w x 23"h
The entry way your dog goes through. Height To Raise Window
30 1/2”
How high you must raise your window in order to fit the panel into the track.| Flap Size | Flap Dimension | Height To Raise Window | Recommended Pet Height |
|---|---|---|---|
| Small | 6" w x 11" h | 18 1/2" | 9" - 15" |
| Medium | 8" w x 15" h | 22 1/2" | 9" - 21" |
| Large | 10" w x 19" h | 26 1/2" | 9" - 27" |
| Extra Large | 12" w x 23" h | 30 1/2" | 9" - 34" |
For your adjustment range, you need to measure the length of your sash window track from the furthest left to right. The adjustment range of your pet door should ideally have your track length in the middle. Custom orders are subject to special restrictions. The following adjustment ranges are available:
- 22"– 25"
- 25"– 28"
- 28"– 31"
- 31"– 34"
- 34"– 37"
- 37"– 40"
- 40"– 43"
Find The Best Pet Door Size For My Pet
A
Pet Height: inches
B
Pet Width: inches
Installation Instructions
Printable Version
Difficulty
Steps
Time Required
Sections
Flags
Parts
- Sash Window Pet Door
- Foam Weather Strip
- Center Post Weather Seal Draft Stopper
- Screwdriver
Tools
- Flathead Screwdriver
Please read instructions & notes thoroughly before installation.
Step 1 Release Spring Mechanism
- Loosen the width adjustment locks at the end of the pet door insert with the screwdriver. This allows the spring mechanism to move freely from side to side.
Step 2 Check Panel Fit
- Insert the sash into the window track. Push against the spring mechanism and swing the opposite end into the opposite window track. Gently release. Tighten the width adjustment locks.
Step 3 Apply Weatherstripping
- Remove panel from window track.
- Apply the foam weather-stripping by peeling back the paper and exposing the adhesive. Unroll it along the edge of the sash, pressing to ensure it adheres. Install on both the top and the bottom. Trim to fit with scissors.
Step 4 Mount Seal Draft Stopper
- Mount the Center Post Weather Seal Draft Stopper. This strip prevents air from leaking between the window frame when raised to accommodate the sash. Trim to fit with scissors.
- Put the panel back into the window track. Tighten width adjustment locks.
Switch the Side of the Flap
You can switch which side of the sash panel the pet door flap is on to best fit your home.
Step 1
- Remove the screws on the top and bottom closest to the edge of the pet door. Then slightly loosen the screws closest to the glass. Next, slide off the side piece, then the flap assembly.
![](https://cdn.shopify.com/s/files/1/0325/4524/3274/files/sash_7.png?v=1626304819")
Step 2
- Rotate the flap assembly (essentially flipping it upside down) then slide it back in. Make sure the locking cover is on the same side as the width adjustment locks.
Step 3
- Replace the end spacer and screws.
LOCKING YOUR WINDOW
For a permanent lock, install a wood screw in the track immediately above the window on both sides. You will no longer be able to raise the window. For a temporary lock, place a removable wooden dowel or Charley bar in either track above the window, shown in Detail 1.
HEIGHT OF YOUR WINDOW
Make sure you place steps or ramps leading to your pet’s door at a height that works! When they go through the flap, the top of the flap should be at least 1" (2,5 cm) higher than the top of their back. Watch your pet and adjust as needed to keep them comfortable.
Videos
Installing a Thermo Sash 3e
How to Measure Your Door for a Sash Window Pet Door
Variable Magnetic Resistance
Replacing the Flap in the Sash Pet Door
Switching Flap Sides
Additional Switch the Side of the Flap
Wind Test
FAQ
|
Does the Thermo Sash have an adjustable height? No, the unit’s height is determined by the height of the pet door. |
|
If my window is not ground level, can I still install a dog door? Yes. There are many creative ways to give your dog access to the window, including installing steps or a ramp on both sides of the window. |
|
Can I change which side (left or right) the flap is on? Yes, you can switch which side of the panel the pet door is on. You start by removing the screws on the top and bottom, then sliding the flap assembly out. Once it is removed you simply flip it upside down and slide it right back in. Next you put the screws back in, tighten them all down and you're finished. You'll want to make sure the thumb screws and locking cover are on the same side. |
|
Is the Thermo Sash available in sizes smaller than the 22" wide? You can make it 3/4" inch smaller by trimming the spring loaded piece on the right side of the panel. If this is not enough, we may be able to make a custom width with less or no glass. Please contact our customer service team with your specific needs for us to review the possibility. |
|
How high do I have to raise my window in order to install the Thermo Sash? It can vary based on the size of your pet door:
|
|
How wide must the window track be to accommodate the Thermo Sash 3e? For installation, your window track must be at least 1 inch wide. |
|
I ordered the wrong size. Is there a way to make my panel bigger? If your door is too short, you can order the patio panel height extension to add additional height. |
|
Which of the Thermo Sashes are considered custom and are not returnable? All Extra Large pet door sashes and any pet door size in a sash width with a 22"-25" adjustment range are considered custom and are not returnable. |
|
What makes the Endura thermo sash so great? There has been lots of discussion as to why the Endura Flap is such a high performing pet door, but for engineers or those looking for some more technical information here is a 74-page‚ dog door energy efficiency study‚ showing what makes it so special. This insulated window cat door will keep your energy bill low. |
Warranty
Endura Flap products have a lifetime warranty against defects in materials and workmanship under standard regular use. Damage caused by not using the product as intended, improper installation, and chewing is not covered under this warranty.Customer Reviews
Customer Reviews
4.8 Based on 43 Reviews
Write a Review Ask a Question - Reviews
- Questions
Filter Reviews:
LB
08/04/2023
Lorrie B.
United StatesGreat cat door
This cat door window was easy to put in. One of my cats still has a little trouble using it. Due to the fact she is somewhat skittish of anything different. Now the other one blew right through it. Less than an hour. He wanted to get in his new Catio!
NS
05/22/2023
Norma S.
United StatesBest in Class
I bought my doggie (window) type door back in January of 2022. It has been the best thing I ever did for my pomerianian. She learned how to use it and when I have to leave for a few hours I have peace of mind she is able to let herself out. Also, when I dogsit her son, he also has learned (from her his mom) how to go in and out the doggie door, so he is not peeing on my furniture in side the house, so no more doggie diapers either. It has been durable to this day. I installed it in a window and it juts right up to my back patio so all I had to do was add some bricks to make it easy for the dog's height. Don't wait! Get it!
PF
08/26/2022
Paul F.
United StatesGreat pet door but the instructions were for a sliding glass door model not the sash window model. We figured it out but the correct instructions would have made it a lot easier!
So far so good!
CG
04/04/2022
Cynthia G.
United StatesThermo Sash 3e Pet Door for Sash Windows
I bought this door for the catio I built outside a bedroom window and it is exactly what I was hoping for. Keeps the cold out and the cat happy. Being able to change which side the flap is on is a huge bonus. It's a well designed window/pet door and built to last. I'm very glad I bought it!
BH
04/04/2022
Barbara H.
United Stateswell made and so easy to install
This product is a life saver for me as I don't have to wake up to my cat crying to go out anymore. I have 3, one conquered it in about 2 weeks (I did put masking tape over the magnets to lessen the strength and I did prop the door open with a jar so that the cats get used to coming and going through it. My second cat is just on the verge and if I push his paw through, he can take it from there. My third is fickle and scared of everything, not sure he'll ever conquer but when the weather is nice and I don't need heat or air, I still prop the door open. I did build a little staircase out of paver stones on both sides to help them get thru and I have a small cat castle on both sides of window portion so that they can look thru while they try to figure it out. Yes, they are beyond spoiled. The window is very well made and we have had some crazy winds and it didn't effect it one way or another.
- Small6"w x 11"h
- Medium 8"w x 15"h
- Large 10"w x 19"h
- Extra Large 12"w x 23"h
Flap Dimensions:
6"w x 11”h
The entry way your dog goes through. Height To Raise Window
18 1/2"
How high you must raise your window in order to fit the panel into the track.Flap Dimensions:
8"w x 15"h
The entry way your dog goes through. Height To Raise Window
22 1/2"
How high you must raise your window in order to fit the panel into the track.Flap Dimensions:
10"w x 19"h
The entry way your dog goes through. Height To Raise Window
26 1/2"
How high you must raise your window in order to fit the panel into the track.Flap Dimensions:
12"w x 23"h
The entry way your dog goes through. Height To Raise Window
30 1/2”
How high you must raise your window in order to fit the panel into the track.| Flap Size | Flap Dimension | Height To Raise Window | Recommended Pet Height |
|---|---|---|---|
| Small | 6" w x 11" h | 18 1/2" | 9" - 15" |
| Medium | 8" w x 15" h | 22 1/2" | 9" - 21" |
| Large | 10" w x 19" h | 26 1/2" | 9" - 27" |
| Extra Large | 12" w x 23" h | 30 1/2" | 9" - 34" |
For your adjustment range, you need to measure the length of your sash window track from the furthest left to right. The adjustment range of your pet door should ideally have your track length in the middle. Custom orders are subject to special restrictions. The following adjustment ranges are available:
- 22"– 25"
- 25"– 28"
- 28"– 31"
- 31"– 34"
- 34"– 37"
- 37"– 40"
- 40"– 43"
Find The Best Pet Door Size For My Pet
A
Pet Height: inches
B
Pet Width: inches
Installation Instructions
Parts
- Sash Window Pet Door
- Foam Weather Strip
- Center Post Weather Seal Draft Stopper
- Screwdriver
Tools
- Flathead Screwdriver
Please read instructions & notes thoroughly before installation.
Step 1 Release Spring Mechanism
- Loosen the width adjustment locks at the end of the pet door insert with the screwdriver. This allows the spring mechanism to move freely from side to side.
Step 2 Check Panel Fit
- Insert the sash into the window track. Push against the spring mechanism and swing the opposite end into the opposite window track. Gently release. Tighten the width adjustment locks.
Step 3 Apply Weatherstripping
- Remove panel from window track.
- Apply the foam weather-stripping by peeling back the paper and exposing the adhesive. Unroll it along the edge of the sash, pressing to ensure it adheres. Install on both the top and the bottom. Trim to fit with scissors.
Step 4 Mount Seal Draft Stopper
- Mount the Center Post Weather Seal Draft Stopper. This strip prevents air from leaking between the window frame when raised to accommodate the sash. Trim to fit with scissors.
- Put the panel back into the window track. Tighten width adjustment locks.
Switch the Side of the Flap
You can switch which side of the sash panel the pet door flap is on to best fit your home.
Step 1
- Remove the screws on the top and bottom closest to the edge of the pet door. Then slightly loosen the screws closest to the glass. Next, slide off the side piece, then the flap assembly.
Step 2
- Rotate the flap assembly (essentially flipping it upside down) then slide it back in. Make sure the locking cover is on the same side as the width adjustment locks.
Step 3
- Replace the end spacer and screws.
LOCKING YOUR WINDOW
For a permanent lock, install a wood screw in the track immediately above the window on both sides. You will no longer be able to raise the window. For a temporary lock, place a removable wooden dowel or Charley bar in either track above the window, shown in Detail 1.
HEIGHT OF YOUR WINDOW
Make sure you place steps or ramps leading to your pet’s door at a height that works! When they go through the flap, the top of the flap should be at least 1" (2,5 cm) higher than the top of their back. Watch your pet and adjust as needed to keep them comfortable.
Videos
Installing a Thermo Sash 3e
How to Measure Your Door for a Sash Window Pet Door
Variable Magnetic Resistance
Replacing the Flap in the Sash Pet Door
Switching Flap Sides
Additional Switch the Side of the Flap
Wind Test
FAQ
|
Does the Thermo Sash have an adjustable height? No, the unit’s height is determined by the height of the pet door. |
|
If my window is not ground level, can I still install a dog door? Yes. There are many creative ways to give your dog access to the window, including installing steps or a ramp on both sides of the window. |
|
Can I change which side (left or right) the flap is on? Yes, you can switch which side of the panel the pet door is on. You start by removing the screws on the top and bottom, then sliding the flap assembly out. Once it is removed you simply flip it upside down and slide it right back in. Next you put the screws back in, tighten them all down and you're finished. You'll want to make sure the thumb screws and locking cover are on the same side. |
|
Is the Thermo Sash available in sizes smaller than the 22" wide? You can make it 3/4" inch smaller by trimming the spring loaded piece on the right side of the panel. If this is not enough, we may be able to make a custom width with less or no glass. Please contact our customer service team with your specific needs for us to review the possibility. |
|
How high do I have to raise my window in order to install the Thermo Sash? It can vary based on the size of your pet door:
|
|
How wide must the window track be to accommodate the Thermo Sash 3e? For installation, your window track must be at least 1 inch wide. |
|
I ordered the wrong size. Is there a way to make my panel bigger? If your door is too short, you can order the patio panel height extension to add additional height. |
|
Which of the Thermo Sashes are considered custom and are not returnable? All Extra Large pet door sashes and any pet door size in a sash width with a 22"-25" adjustment range are considered custom and are not returnable. |
|
What makes the Endura thermo sash so great? There has been lots of discussion as to why the Endura Flap is such a high performing pet door, but for engineers or those looking for some more technical information here is a 74-page‚ dog door energy efficiency study‚ showing what makes it so special. This insulated window cat door will keep your energy bill low. |
Warranty
Endura Flap products have a lifetime warranty against defects in materials and workmanship under standard regular use. Damage caused by not using the product as intended, improper installation, and chewing is not covered under this warranty.Customer Reviews
Customer Reviews
4.8 Based on 43 Reviews
Write a Review Ask a Question - Reviews
- Questions
Filter Reviews:
LB
08/04/2023
Lorrie B.
United StatesGreat cat door
This cat door window was easy to put in. One of my cats still has a little trouble using it. Due to the fact she is somewhat skittish of anything different. Now the other one blew right through it. Less than an hour. He wanted to get in his new Catio!
NS
05/22/2023
Norma S.
United StatesBest in Class
I bought my doggie (window) type door back in January of 2022. It has been the best thing I ever did for my pomerianian. She learned how to use it and when I have to leave for a few hours I have peace of mind she is able to let herself out. Also, when I dogsit her son, he also has learned (from her his mom) how to go in and out the doggie door, so he is not peeing on my furniture in side the house, so no more doggie diapers either. It has been durable to this day. I installed it in a window and it juts right up to my back patio so all I had to do was add some bricks to make it easy for the dog's height. Don't wait! Get it!
PF
08/26/2022
Paul F.
United StatesGreat pet door but the instructions were for a sliding glass door model not the sash window model. We figured it out but the correct instructions would have made it a lot easier!
So far so good!
CG
04/04/2022
Cynthia G.
United StatesThermo Sash 3e Pet Door for Sash Windows
I bought this door for the catio I built outside a bedroom window and it is exactly what I was hoping for. Keeps the cold out and the cat happy. Being able to change which side the flap is on is a huge bonus. It's a well designed window/pet door and built to last. I'm very glad I bought it!
BH
04/04/2022
Barbara H.
United Stateswell made and so easy to install
This product is a life saver for me as I don't have to wake up to my cat crying to go out anymore. I have 3, one conquered it in about 2 weeks (I did put masking tape over the magnets to lessen the strength and I did prop the door open with a jar so that the cats get used to coming and going through it. My second cat is just on the verge and if I push his paw through, he can take it from there. My third is fickle and scared of everything, not sure he'll ever conquer but when the weather is nice and I don't need heat or air, I still prop the door open. I did build a little staircase out of paver stones on both sides to help them get thru and I have a small cat castle on both sides of window portion so that they can look thru while they try to figure it out. Yes, they are beyond spoiled. The window is very well made and we have had some crazy winds and it didn't effect it one way or another.
Lifetime Warranty
Fast Shipping
100% Secure Checkout
Easy Returns
